This invention relates to `bionic dunes` which can best be defined as the re-creation of eroded and missing natural primary ocean-front sand dunes, but with a very necessary improvement which would make them non-eroding, and thereby worth re-creating.
Their purpose and functions are two-fold, as they would not only protect the upland topography of barrier islands (commonly called `barrier beaches`) and the mainland behind them from increasingly powerful hurricanes, such as the type that recently ravaged the southeastern coastal states of the continental United States, but also be restorers, equalizers and stabilizers of the beaches and shorelines on their seaward side. The reasoning behind these important additional functions is given below, based on over 60 years of observation as a resident real property owner of two houses in two communities on a `barrier beach`, one of which has been in the inventor's family for more than 82 years. The other was built in 1951; both are still owned by him and have given him constant opportunities to study one beachfront with dunes and the other without dunes. He has, over many years, observed with intense interest the interactions between ocean surf-waves during severe storms and high tides, in all seasons, and the two separate sand-beach shorelines when with and without their natural primary sand dunes.
The principle in the creation of `bionic dunes` is to provide non-eroding `civilization resistant` oceanfront primary sand dunes systems embodying a passive (non-colliding) method of ocean surf-wave control without the fragility of the all-natural dunes with their inability to survive the many varieties of damage, such as: building on, treading on, driving on with off-road vehicles, and damages from construction machines, trucks and bulldozers disfiguring their bases, plus general acts of total disregard and/or ignorance of their importance in the balances nature brings to its diverse processes within the relationship between primary dunes and their adjacent beaches. Most of said damage has been done in the last 60 years.
A symmetrical primary oceanfront sand-dune line, in observing reciprocal processes after a series of waves have broken on a beach which is backed by a gently rising sand-dune base, is seen to lead each on-rush of sand-bearing water quickly, smoothly and quietly uphill to a `stall-point`, where the water loses its momentum, falls back toward the berm of the beach, at which time its sands in suspension begin to fall out while much of the slowly moving water is being absorbed in the porous sands of the berm of the beach, as the remaining water, if any, is met by a subsequent run of sand-carrying wave-water coming in across the berm, headed for the base of the dunes, repeating the process just described. This process, repeated every minute, for hours, days, and nights until either high tides, storms or water-surges abate, adds great amounts of sand to a beach from the dunes' base, seaward, over the berm, and to the edge of the shoreline.
The same weather and tide conditions prevailing, on a stretch of beach with no dune line, therefore: no inclined dunne-base, `stall point`, would allow the same water mass to race over and past the upland end of the berm and over the sands where a dune-line should have been, and continue into the inner parts of the island without depositing its sands in suspension on any part of the beach area. If this rush-over of water continues, it could begin eroding the area of the old dune-line over which it now rushes. Within hours a breakthrough `cut` could become deep-enough to look like a stream-bed, later like a riverbed, and thereafter an inlet is created. This explains how important the presence of primary oceanfront sand dunes are to adjacent beach preservation.
In areas where primary dunes were sufficiently damaged to lose their effectiveness as described above, the adjacent beaches began to suffer from increasing erosion. It was at that time that community managers and property owners, in some of the affected communities, began to show interest in erecting sand-catching barriers on their beaches. Still not aware that the loss of dunes could have any bearing on their beach problems, they concentrated on securing federal, state or county funds to install rock groins at a 90 degree angle to the beaches. Other blunt confrontational structures also came into vogue, such as jetties, seawalls, revetments, sta-pods and offshore rockpiles. Soon after installation of any one of the foregoing, off and on the shorelines of many eastcoast states, extremely damaging side-effects were connected to their presence. Groins produced `scouring action` on the downdrift side of the littoral drift off Long Island, N.Y., causing loss of as much as half the width of beach for thousands of yards down the beach. Jetties caused uncontrolled sand deposits on their updrift side with sand overflowing the jetties' landward rocks and being washed into the inlet it was designed to protect, forming unwanted shoal waters and sandbars as well as accretion on the opposite bank of the inlet. Seawalls, built along upland sides of beach berms caused a single-wall sluiceway effect, resulting in complete loss of entire beaches, such as along the `Jersey Shore` in New Jersey, south of N.Y. harbor. Revetments cannot be considered to be much better than seawalls, because, they, too, can be undercut at their bases and moved into disarray in heavy storms, losing their ability to protect much of anything. Sta-pods and indiscriminately dumped rockpiles of small and large rocks cause underwater currents to disperse, creating underwater turmoil, sending currents in any direction, resulting in unpredictable erosion of a shoreline.
The message we should get from the foregoing observations is that blunt confrontational structures, in attempting to control surfwave action, only cause more damage than they were installed to prevent. We also must conclude that the only successful method is that of passive control wherein heavy, powerful masses of fast-moving water, from breaking waves on a beach, can be guided up the gentle slopes of dune-bases to an increasingly greater incline until a `stall-point` is reached, not only causing each wave to stop and return seaward, but to deposit its sands in suspension in such a beneficial way that the dunes are also instruments of sand nourishment to the adjacent beach, and therefore also a stabilizing force in the best methods known to man--the natural scheme of things.
In view of the foregoing, it certainly would be rational to conclude that if blunt confrontational structures are removed from oceanfront sand beaches and only the passive method of wave-water control, as described above, is applied to such beaches, there should be dependable beach build-up and stabilization easily tolerating the normal, temporary, yearly cyclical erosion and accretion, from fall and winter, to spring and summer months, caused by seasonal changes along, for example, Long Island's oceanfront beaches, where, with a constant west-flowing littoral drift, the winds and storms in the cold months prevail out of the northeast, but the winds and storms in the warm months prevail from the southwest. The two easterly forces, combined in `winter` erode the beaches, but the two opposing forces in `summer` cause opposite-moving water-borne* sands to fall out of suspension at the points of contact occurring along the shoreline of those beaches, causing predictable restoration of the shoreline in time for the summer season.
If only passive processes are put back to work there would be every reason to expect that we would again have wide, stabilized beaches paralleling those indispensable sand-nourishment tools of the ages--the primary oceanfront sand dunes, which aid in building higher berms which could offset the sort of alleged consequences as stated in the following:
The questionable theory that such beaches will be diminished in width by a rise in sea-level rate of a foot by the year 2000; one foot, three inches by 2010; and three feet by 2040, has been disputed by a recently publicized contention that the `greenhouse effect`, caused by global warming from planet-wide carbon emissions, by the year 2000 shall not be permitted to continue, as international agreements are being reached to eliminate all present sources to be replaced by non-polluting alternative energy sources. Therefore, the future for our shorelines now appears to be brighter and `bionic dunes` can be built without fear of their having to retreat from a steadily encroaching ocean, as apathy and ignorance is conquered in the proper treatment of our planet.
A number of U.S. Pats. have been issued which deal with beach destruction and related problems.
U.S. Pat. No. 20,105 issued in 1858, which illustrates how far back man has been dealing with this problem, discloses a sea wall consisting of a frame containing stones.
U.S. Pat. No. 591,256 shows a system of plants arranged to protect levees.
U.S. Pat. No. 1,428,808 illustrates the use of partially embedded walls to prevent the undermining of water washed banks.
U.S. Pat. No. 2,190,003 discloses the use of stone-settings on a sandy subsoil and the injection of a stabilizing agent under the stones for fixing and immobilizing water front property.
U.S. Pat. No. 4,345,856 describes the stabilization of embankments utilizing the development of growth on the embankment.
U.S. Pat. No. 4,362,432 shows the use of a sea wall with an energy dissipating and absorbing structure for preventing the erosion of beaches.
U.S. Pat. No. 4,367,978 describes apparatus for halting beach erosion employing prism-shaped slotted modules placed in the wave breaking areas.
U.S. Pat. No. 4,498,805 describes a breakwater made of modules designed to trap the wave water and to dissipate the energy in so-called water-to-water interactions.
U.S. Pat. No. 4,521,131 illustrates a lightweight semi-flexible dike made up of layers of mixtures of shells, sand and cement and the water side of the dike covered with a dike cover which is permeable to the water.
U.S. Pat. No. 4,804,293 discloses a flexible layer structure for use in covering earthworks subject to water contact.
None of the preceding patents teaches or suggests the present invention.